Extrusion apparatus for coating both surfaces of tubular material

ABSTRACT

This disclosure relates to a process and apparatus for the continuous coating of a tube of fiber material with viscose, the process comprising conveying the tube so that its wall traverses a cylindrical zone of a width of 0.3 to 1.0 mm, defined by external and internal elements, and in its progress through said zone is coated with viscose first on the exterior and then on the interior thereof.

United States Paten 1191 Kindl et a1. l

1451 July 29,1975

. BOTH SURFACES 0F TUBULAR Filed:

' Appl. No.: 380,274

EXTRUSION APPARATUS FOR COATING MATERIAL lnventors: Erwin Kind],Wiesbaden-Blebrich; Giinter Gerick, Oberursol, both of Germany l-loechstAktiengesellschatt, Germ any July 18,1973

Assignee:

Related U.S. Application Data Continuation of Ser. No. 193,524, Oct. 28,1971, abandoned, which is a division of Ser. No. 100,916,

Dec. 23, 1970, Pat. No. 3,709,720."

Foreign Application Priority Data *Dec. 27, 1969 Germany 1965130 Us. C1.118/408; 118/411; 425/113 1m. C1. B05c 3/12 8] Field of Search 1l8/DIG.10, DIG. 11, 411,

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 536,602 l/1957Canada 118/D1G. 10 601,670

2/1-960 Italy ll8/D1G. 11

Primary Examiner-Morris Kaplan Attorney, Agent, or F irm-J ames E. Bryan[57] ABSTRACT This disclosure relates to a process and apparatus for thecontinuous coating of a tube of fiber material with viscose, the processcomprising conveying the tube so 4 Claims, 1 Drawing Figure |q 50 8e si51 5 li) 3 6o 4o 1 6i 20 8f 1 4i 8171i EXTRUSION APPARATUS FOR COATINGBOTH SURFACES F TUBULAR MATERIAL This is a continuation, of applicationSer. No. 193,524, filed Oct. 28, 1971, now abandoned and which was inturn a division of application Ser. No. 100,916, filed Dec. 23, 1970,now U.S. Pat. No. 3,709,720.

This invention relates to apparatus for coating a tube of fiber materialwith viscose by extrusion.

Fiber-reinforced tubes of regenerated cellulose are known which consistof a tube of fiber material coated on the outside and inside with alayer of regenerated cellulose and which tube is filled more or lesscompletely with regenerated cellulose located between the fibers. Thetube of fiber material is formed from a web of fiber fleece by bondingtogether the overlapped edges of the web. The seam is preferably bondedwith viscose. The application of the two coatings of viscose is carriedout with the aid of annular dies in conjunction with a backing elementwhich supports the tube when the viscose is forced onto it from theannular dies. When applying the outer coating, an annular die isemployed which forces the viscose inwards and which surrounds thebacking element, whereas when the inner coating is applied an annulardie is used which forces the viscose outwards and is surrounded by anannular backing element. In U.S. Pat. Nos. 2,105,273 and 2,144,900 it isstated that the apparatus described therein can be used for coating bothsides of a tube. In one of the above-mentioned patent specifications anannular die is described suitable for applying the outer coating ofviscose, and the tube of fiber material, directly after the applicationof the viscose, is passed through a cylindrical passage between theannular die and a backing element. The tube, provided with the twocoatings of viscose, is then subjected to various further treatmentshaving, among others, the purposes of coagulating the viscose andregenerating it to form cellulose, washing the tube, incorporating aplasticizer into it, and drying it.

in producing fiber-reinforced cellulose tubes by applying a coating ofviscose on only one side of the tube, it has been found expedient onlyto pass the tube into the setting bath, in which the viscose iscoagulated and regenerated partially or completely to form cellulose,after the viscose has fully penetrated the tube. if coagulation takesplace before the tube is fully penetrated by the viscose, then there isfinally obtained a fiberreinforced cellulose tube of lower strength andpoorer transparency than is the case when coagulation and regenerationare carried out after complete saturation of the tube of fiber materialby the viscose.

The penetration of the viscose into the tube of fiber material requiresa certain time, as does the coagulation of the viscose in the settingbath. Since, during the continuous production of fiber=reinforeed tubesof re generated cellulose by the above=described method, the coating ofthe tube with viscose and the coagulation of the viscose coatings mustbe carried out while the tube is moving downwards, without being laidflat, the height of the plant used increases with the requiredproduction rate and the length of time needed for the penetration of theviscose into the tube and for coagu= lation of the viscose.

The present invention provides an apparatus for the continuous coatingof a tube of fiber material with vis= cose, wherein the tube is so.conveyed that its wall tra= verses a cylindrical passage of a width of0.3 to 1.0 mm,

defined by external and internal elements, and in its progress throughthis passage is coated with viscose first on the exterior and then onthe interior. This process reduces the amount of space and time requiredfor the coating of a tube of fiber material on both sides with viscose.

The invention further provides an apparatus inlcuding as an externalelement an annular slot die with the slot directed internally towardsthe passage and as an internal element an annular slot die with the slotdirected externally towards the passage, the arrangement being such thatthe passage has the indicated width and external and internal coating ofthe tube can be carried out in the indicated sequence. The distance fromthe exit opening of the passage through which the tube passes at whichthe viscose is applied to the inside of the tube depends upon theselected width of the pas sage through which the tube passes. Thedistance is between 1 and 50 mm and must be the greater the greater thewidth of the passage. The thinner the fiber fleece of which the tube ismade, the greater, as a rule, the width within the stated limits of 0.3and 1.0 mm. Advantageously, the following relationships are observedbetween the widthw of the passage through which the tube passes and thedistance a between the slot in the inner die and the exit opening(values in mm):

a l-S The distance a is measured from the exit opening to the nearestedge of the annular slot in the inner die. intermediate values betweenthose shown in the above table of relationships can, of course, be used.

The same limits apply to the distance over which the tube is passedbetween the application of the viscose to its outside and theapplication to its inside. Here, it required, relatively short distancescan be used. The distance over which the tube is passed in the passageprior to the application of viscose to the outside of the tube is suchthat no viscose escapes at the entry opening of the passage throughwhich the tube passes. For this purpose, a distance of travel of atleast 2 mm is generally necessary. Advantageously, this distance is keptwithin the above-state limits for the distance a.

in the production of fiber-reinforced synthetic sausage casings made ofregenerated cellulose for which the method is primarily intended, use ismade in most cases of fiber fleeces having a thickness of 0.06 to 0.12mm. The above-mentioned and following details relating to dimensionssuch as length and width of the passage through which the tube passesand the distances of the slots in the annular dies from one another orfrom the entry or exit openings, respectively, of the passage throughwhich the tube passes apply in the case of fiber fleeces of the abovethicknesses.

in the process utilizing the apparatus of the invention the viscose isexpediently applied to the inside of the tube of fiber material at thelatest one second after the application of viscose to the outside of thetube, and advantageously the two applications of viscose take place withan interval of 0.003 to 0.3 second. The rate at which the operation iscarried out, i.e. the rate of travel of the tube of fiber material, canbe 20 meters/- rninx or more.

Generally, the passage through which the tube passes is of the samewidth from the entry opening to the exit opening. The width may varywithin the length of the passage but preferably any variation is at most0.2 mm. However, the approach to the entry opening and the departurepath from the exit opening may, if desired, be convergent and divergent,respectively.

The apparatus of the invention is further illustrated diagrammaticallyby way of example in the accompanying drawing, the single FIGURE ofwhich is a crosssection of the apparatus.

Referring to the drawing, the apparatus consists of an outer annular dieand an inner annular die located therein, each of the two diesconsisting of two parts, i.e. an upper part la and 1i respectively and alower part 2a and 2i respectively.

The outer annular die la, 2a has a central cylindrical bore, the wall ofwhich is formed by an upper lip 3a and a lower lip 4a of the die. Thetwo component parts 1a and 2a of the die form an annular chamber 60 intowhich leads a feed pipe 5a. The annular chamber 6a is for receivingviscose which is forced into it through the feed pipe 5a. The viscosepasses from the annular chamber 6a into an annular slot 7a which entersthe cylindrical bore between the two lips 3a and 4a of the die.

The inner annular die 1i, 2: is located in the central bore of the outerannular die in, 2a. The outer wall of this inner die are formed by anupper lip 3i and a lower lip 41' of the inner die. The two componentparts 11' and 21 likewise form an annular chamber 6i.

A feed pipe 5i enters this chamber. The annular chamber (ii is also usedfor receiving viscose which is forced into it through the feed pipe 5i.The viscose passes from the annular chamber 6: into an annular slot 7!which is formed between the lips 3i and 4: of the die and extendsthrough the outer wall of the annular die 1i, 2:.

Between the outer die lips 30 and 4a on the one hand and the inner dielips 3i and 4! on the other there is a cylindrical annular passage 8 bywhich the tube passes through the apparatus. its entry opening isdesignated by the reference symbol 8e, and its exit opening by 8f. Theupper lip 31 of the inner annular die constitutes a backing element forthe outer annular die 1a, 2a, and the lower lip 4a of the outer annulardie 1a, 2a at the same time constitutes a backing element for the innerannular die 1i, 2!.

The two annular dies in, 2a and it, 21 are secured to a common theme insuch a manner that they can be lined up coaxlally with one another. Theframe, the means for securing the two annular dies to it and thecentering device are of known type and are not illus= trated in thedrawing.

in the drawing, the tube of fiber material that is to be coated isdesignated by the numeral 9, and its over= lapped seam by the numeral10.

Thc'values a and w referred to above can be easily related to theaccompanying drawing. Preferably, the distances between the entryopening of the passage for the tube and the annular slot of the externaldie and be= tween the annular slot or the internal die and the exitopening of the passage for the tube are at least 2 mm and at least threetimes the width of the passage. They are preferably 3 to mm and thewidth of the passage through which the tube passes is preferably 0.4 to0.8 mm. Frcferably, none of the three distances referred to above isgreater than 50 min. Greater distances would not bring about anyadditional advantages in the invention, but would cause the disadvantagethat more material would be used for constructing the apparatus and theapparatus would become unnecessarily long.

For widths w other than those given it is preferable to usecorresponding intermediate values for a, as indicated. The followingrelationship appears to apply, with good approximation to valuesobtained in practice, for the preferable minimum value of the distance ain relation to the width w (both measure in mm):

min 5 X a minimum value of 1 being used, however, if this equationresults in a smaller distance. The following relationship seems toapply, with good approximation to values obtained in practice, for thepreferred maximum value of the distance:

a 50 X w.

The annular slots in the two annular dies usually have a width of lessthan 1 mm, and their length, in the radial direction, is usually only afew millimeters, i.e. 2 to 3 mm. However, neither the width nor thelength of the annular slots 7a and 7i appears to have an appreciableeffect upon the maximum rate at which the tube of fiber material can becoated with viscose, without failure of the viscose to completelysaturate the tube or other undesirable effects occurring during theproduction of a fiber-reinforced cellulose tube. The amount of viscoseper unit area applied to the tube of fiber material depends upon thequantity of viscose which is forced through the annular slots (7a and71') of the two dies during unit time, the rate of travel of the tubethrough the apparatus being the same. The total quantity of viscoseapplied can be distributed in widely varying proportions over theoutside and inside of the tube of fiber material.

The annular slots in the two dies are preferably directedperpendicularly to the passage through which the tube passes, but can,however, also extend towards it at a downwardly inclined angle.

The apparatus of the invention is suitable for coating with viscose bothsides of tubes of fiber material which are made from fiber fleeceshaving a thickness of approximately 0.06 to 0.12 mm. Tubes of fibermaterial having diameters of 30 mm or more can be coated. There appearsto be no upper limit as regards diameter, since tubes of fiber materialof relatively large diameter up to mm have been successfully coatedusing the apparatus of the invention.

The method and apparatus of the invention enable viscose to be appliedsuccessively to the two sides of a tube of fiber material in arelatively short apparatus. The method and apparatus also offer theadvantage that the viscose applied to the tube of fiber material rapidlypenetrates into the tube. Thus, with a prescribed height of coatingapparatus, it is possible to carry out two=sided coating more rapidlythan previously, since the tube does not travel any great distancebetween the points at which the two layers of viscose are applied, andafter leaving the apparatus to the point at which the viscose has fullypenetrated the tube, the latter has to travel through the air over onlya relatively short distance, so that the coagulating bath for theviscose can be made correspondingly deeper and the tube can be passedthrough it more rapidly. Conversely, it becomes possible to achieve aprescribed operating rate with coating equipment, the height of which isless than heretofore. The method and the apparatus also offer theadvantage that good results are obtained even when no separate step inthe method is used for bonding the overlapping edges of the fiberfleece,the bonding of the overlapped portions instead taking place incidentallyas a result of the external and internal coating of the tube of fibermaterial with viscose. The method is preferably performed in thismanner, that is, without a separate operation for bonding the overlappedseam.

The following Examples further illustrate the invention:

EXAMPLE 1 For producing a fiber-reinforced cellulose casing coated onboth sides with cellulose, use was made of apparatus having thefollowing dimensions:

The annular slots in both dies were perpendicular to the passage throughwhich the tube passes.

The surface of the coagulating bath was at a distance of 50 cm from theapparatus (travel through air). As a result of this short distance oftravel through the air, which was determined to enable the apparatus tobe operated in an improved manner, it was possible, in the same space asusual, to employ a 3-meter high coagulating tank instead of the 2-meterhigh tank previously used when applying a viscose coating on one sideonly of the tube. The distance of travel of the fiber fleece coated onboth sides with viscose, from the point of entry into the coagulatingbath to a lower guide roller (where the tube is flattened) was 2.60meters.

The coagulating bath contained g/l (gram per liter) of sulfuric acid and150 g/l of ammonium sulfate. The fiber fleece was a standard commercialproduct as used in the manufacture of casings of fiber material and hada weight of 21 g per square meter, a thickness of 0.09 mm and a width of204 mm. Bonding of the overlapping strip of fleece with viscose was notcarried out as a separate step since this was accomplished incidentallyby the viscose penetrating the fleece from the outward and inwarddirections.

Under the conditions described above, and at a speed of passage of 22m/min (meters per minute), a fiber casing (synthetic cellulose casingwith a fiber fleece base) of excellent appearance and very greatstrength was obtained. Furthermore, by using the apparatus described andby varying the quantities of viscose fed to the two annular nozzles, itwas possible to effect a wide variation of the amount of viscose appliedexternally and internally. For example, a fiber casing having a weightper square meter of 95 g was produced, on

which 50 per cent of the viscose was applied from the inside and 50 percent from the outside.

EXAMPLE 2 For producing a fiber-reinforced cellulose casing coated onboth sides, use was made of apparatus having the followingdimensions:

The annular slots in both dies were perpendicular to the passage throughwhich the tube passes.

The annular slots in both dies were perpendicular to the passage throughwhich the tube passes.

The distance between the apparatus and the surface of the coagulatingbath was 50 cm, and the distance from the surface of this bath to alower guide roller (where the tube is flattened) was 2.60 m.

The coagulating bath contained 15 g/l of sulfuric acid and 130 g/l ofammonium sulfate. The fiber fleece had a weight per square meter of 17g, a thickness of 0.07 mm and a width of 204 mm. per cent of the viscosewas applied on the outside and 30 per cent on the inside. At a speed ofpassage of 20 m/min. a very transparent, parchment-like fiber casing ofexcellent strength was obtained.

In the above Examples, the time required for the viscose to penetrateinto the fiber fleece was 1.5 see. This time could be further reducedwithout adversely affecting the quality of the product.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:

1. An apparatus for use in the continuous coating of a tube of fibermaterial with viscose which comprises a cylindrical passage having awidth of about 0.3 to 1.0 7

mm, first annular slot die means having the slot thereof directedinwardly toward said cylindrical passage and in open communicationtherewith, second annular slot die means having the slot thereofdirected outwardly toward said cylindrical passage and in opencommunication therewith, said first and second slot die means beingoffset from one another along said cylindrical passage such that a tubeof fiber material conveyed through said cylindrical passage is coatedwith viscose, first on the exterior thereof and then on the interiorthereof, first viscose feed means in open communication with said firstslot die means and second viscose feed means in open communication withsaid second slot die means, the distance between the first and thesecond slot die means, the distance of said first slot die means fromthe entry opening of the cylindrical passage for the tube and thedistance of said second slot die means from the exit opening of saidcylindrical passage for said tube being not more than 50 mm.

2. An apparatus as claimed in claim 1 in which the distance between theentry opening of the cylindrical passage for the tube and the first slotdie means and the distance between the exit opening of the cylindricalpassage for said tube and the second slot die means are at least 2 mmand at least three times the width of said cylindrical passage.

3. An apparatus as claimed in claim 2 in which the distance of the firstslot die means from the entry opening of the cylindrical passage for thetube and the distance of the second slot die means from the exit openingof said cylindrical passage for said tube are at least 2 mm, but notless than 5 w and not more than 50 w, where w is the numerical value ofthe width of said cylindrical passage in millimeters.

4. An apparatus as claimed in claim 1 in which the distance of the firstslot die means from the entry opening of the cylindrical passage for thetube and the distance of the second slot die means from the exit openingof said cylindrical passage are 3 to 15 mm and the width of saidcylindrical passage is 0.4 to 0.8 mm.

'[SEAL] UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.2 3,896,764

DATED July 29, 1975 INVENTOR(S) Erwin Kindl and Gt'inter Gerigk It iscertified that error appears in the ab0ve-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Item [75' line 2 thereof, "Cerick" should read Gerigk Column 2, lines 8and 9, "inlouding" should read including Line 47, "above-state" shouldread above-stated Column 3, line 27, "Wall" should read Walls Line 48,"aecured" should read secured Column 4, line 10, "measure" should readmeasured Line 61 after "apparatus" insert and Column 6', delete lines 22thr ugh 24.

Signed and Scaled this ninth Day of December 1975 A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofParenrsand Trademarks

1. An apparatus for use in the continuous coating of a tube of fibermaterial with viscose which comprises a cylindrical passage having awidth of about 0.3 to 1.0 mm, first annular slot die means having theslot thereof directed inwardly toward said cylindrical passage and inopen communication therewith, second annular slot die means having theslot thereof directed outwardly toward said cylindrical passage and inopen communication therewith, said first and second slot die means beingoffset from one another along said cylindrical passage such that a tubeof fiber material conveyed through said cylindrical passage is coatedwith viscose, first on the exterior thereof and then on the interiorthereof, first viscose feed means in open communication with said firstslot die means and second viscose feed means in open communication withsaid second slot die means, the distance between the first and thesecond slot die means, the distance of said first slot die means fromthe entry opening of the cylindrical passage for the tube and thedistance of said second slot die means from the exit opening of saidcylindrical passage for said tube being not more than 50 mm.
 2. Anapparatus as claimed in claim 1 in which the distance between the entryopening of the cylindrical passage for the tube and the first slot diemeans and the distance between the exit opening of the cylindricalpassage for said tube and the second slot die means are at least 2 mmand at least three times the width of said cylindrical passage.
 3. Anapparatus as claimed in claim 2 in which the distance of the first slotdie means from the entry opening of the cylindrical passage for the tubeand the distance of the second slot die means from the exit opening ofsaid cylindrical passage for said tube are at least 2 mm, but not lessthan 5 w2 and not more than 50 w2, where w is the numerical value of thewidth of said cylindrical passage in millimeters.
 4. An apparatus asclaimed in claim 1 in which the distance of the first slot die meansfrom the entry opening of the cylindrical passage for the tube and thedistance of the second slot die means from the exit opening of saidcylindrical passage are 3 to 15 mm and the width of said cylindricalpassage is 0.4 to 0.8 mm.